As a technology for removing a high-dose ion implanted resist formed on a substrate, there have been proposed various techniques that are disclosed in the following Patent Documents.
A plasma treatment method and an apparatus that practically uses the method are disclosed in Patent Document 1 in which a plasma treatment is applied to a substrate using a helicon wave plasma treatment with the aid of a substrate bias induction means and a substrate heating means. Concretely, a resist mask formed on a substrate is removed by employing both an ion mode heavy plasma treatment using a high ion current with a helicon wave plasma and a radical mode heavy plasma treatment using an non-resonance inductive coupling plasma.
Another plasma treatment method and an apparatus that practically uses the method are disclosed in Patent Document 2 in which an ashing treatment is applied to a hardened degeneration layer of a resist mask on a substrate by a plasma treatment device that has a helicon plasma generator with a transparent bell-jar made of a dielectric material that is transparent to an UV light. In a subsequent step, a non-degeneration layer of the resist mask on the substrate is subjected to an ashing by an UV light radiation in ozone gas.
A resist removing method and an apparatus that practically used the method are disclosed in Patent Document 3 in which a substrate is heated to cause a resist on a surface of a substrate to have a popping phenomenon. After the substrate is cooled, the resist is peeled off by using an adhesive tape and then an ashing is continuously carried out by a combination of oxygen plasma and ozone gas or that of an UV light and ozone gas.
In a high-dose ion implanted resist, a hardened layer is formed on the surface of the substrate like a film. Since a soft resist (non-degeneration layer) is provided beneath the resist, heating the substrate at a high temperature, for example, above 400° C. tends to induce so-called popping phenomenon in which the surface of the substrate is cracked and blown off by an exhaust gas from the non-degeneration under layer and a thermal expansion difference. The blown off hardened layer of the substrate surface contaminates not only the substrate but also an interior of a chamber that holds therein the substrate. Accordingly, the resist removing method described in Patent Document 3 by way of example in which a heating process is used fails to have a satisfied yield of production of devices. Furthermore, since it is necessary to shorten a maintenance interval of production machines, throughout of the substrates is affected.
While, the treatment methods disclosed in Patent Documents 1 and 2 are suppressed from suffering from the popping phenomenon. However, in such methods, it is necessary to provide a plasma generator. The Plasma generator is expensive and if such plasma generator is provided, an device for removing the resist is entirely increased in size. Furthermore, it causes increase in cost of energy required for a resist removing.                Patent Document 1: Japanese Laid-open Patent Application (Tokkaihei) 8-69896.        Patent Document 2: Japanese Laid-open Patent Application (Tokkaihei) 8-139004.        Patent Document 3: Japanese Laid-open Patent Application (Tokkaihei) 9-27473.        